To maintain product quality, manufacturers of semiconductor devices perform tests on their products prior to shipment to consumers. During testing, one or more devices-under-test (DUTs) are stimulated by signals from automatic test equipment (ATE) which is configured to receive and analyze the responses from the DUTs. As an example, DUTs can include dies on a wafer or integrated circuit (IC) chips. The stimuli and responses between the ATE and the DUTs are passed through interface equipment, including a contact mechanism that makes electrical contact with contact surfaces of the DUTs. By analyzing the responses of the DUTs to the stimuli, the ATE can determine whether a given DUT is to be accepted or rejected.
For example, during probe testing of a wafer, the contact mechanism can include a probe card affixed to a prober, such that the prober maneuvers a wafer to bring the contact surfaces of dies into electrical contact with needles of the probe card. As another example, during testing at a final stage of production, the contact mechanism can be a load board containing IC receptacles with contact pins, such that a handler manipulates IC chips and plugs them into the IC receptacles. Thus, a given contact mechanism, such as a probe card or a load board, is used to make electrical connections with contact surfaces of the DUTs to deliver stimuli and receive responses, respectively, between the ATE and the DUTs for a determination of whether a given DUT is to be accepted or rejected.
Contact surfaces of dies or IC chips, as well as electrical contacts of the contact mechanism may be formed from metals that can oxidize (e.g., aluminum, tin, and/or copper). As a result, the action of making contact cuts and/or scrubs through a formed oxide layer may result in the flaking-off and/or accumulation of debris. Oxides, debris from repeated contact action, moisture from the humidity controlled test environment, and/or contaminates inherent to semiconductor processes can adhere to the contact surfaces of the contact mechanism, degrading connectivity performances. Therefore, stimuli and responses between the ATE and the DUTs can become distorted, thus introducing the possibility of false negative test results. Accordingly, a semiconductor manufacturer can lose money by scrapping devices that falsely fail tests through unreliable test data measurements.
Typically, a semiconductor device manufacturer can occasionally clean the electrical contacts of the contact mechanism to remove debris and/or restore conductivity. Automated periodic cleaning may be used to clean the electrical contacts of the contact mechanism, such that user specified parameters govern when and how cleaning is to be performed. Typically, these parameters are set so as to preserve reliable test results under worst-case scenarios. Therefore, after cleaning the contact mechanism, reliable testing of the DUTs may be assured. However, cleaning too often or too aggressively can result in excessive mechanical wear of the contact surfaces of the contact mechanism. Thus, the useful life of a contact mechanism can be shortened, resulting in a need for frequent replacement at elevated testing costs.